Document Type
Article
Publication Date
8-10-2011
Publication Title
Letters of the Astrophysical Journal
Department
Department of Physics and Astronomy
Abstract
We report the discovery of a bright (V ~ 13.7), extremely low-mass white dwarf in a close double degenerate system. We originally selected GALEX J171708.5+675712 for spectroscopic follow-up among a group of white dwarf candidates in an ultraviolet-optical reduced proper-motion diagram. The new white dwarf has a mass of 0.18 M_solar and is the primary component of a close double degenerate system (P=0.246137 d, K_1 = 288 km/s) comprising a fainter white dwarf secondary with M_2 ~ 0.9 M_solar. Light curves phased with the orbital ephemeris show evidence of relativistic beaming and weaker ellipsoidal variations. The light curves also reveal secondary eclipses (depth ~ 8 mmag) while the primary eclipses appear partially compensated by the secondary gravitational deflection and are below detection limits. Photospheric abundance measurements show a nearly solar composition of Si, Ca, and Fe (0.1-1 solar), while the normal kinematics suggest a relatively recent formation history. Close binary evolutionary scenarios suggest that extremely low mass white dwarfs form via a common-envelope phase and possible Roche-lobe overflow.
DOI
10.1088/2041-8205/737/1/L16
Dartmouth Digital Commons Citation
Vennes, S.; Thorstensen, J. R.; Kawka, A.; Németh, P.; and Skinner, J. N., "Discovery of a Bright, Extremely Low Mass White Dwarf in a Close Double Degenerate System" (2011). Dartmouth Scholarship. 1798.
https://digitalcommons.dartmouth.edu/facoa/1798
